Description

Shared Lane Markings (SLMs), or “sharrows,” are road markings used to indicate a shared lane environment for bicycles and automobiles. Among other benefits shared lane markings reinforce the legitimacy of bicycle traffic on the street, recommend proper bicyclist positioning, and may be configured to offer directional and wayfinding guidance. The shared lane marking is not a facility type, it is a pavement marking with a variety of uses to support a complete bikeway network. The MUTCD outlines guidance for shared lane markings in section 9C.07.

Click on the images below to view 3D concepts of shared lane markings. The configurations shown are based on Portland, OR, and San Francisco, CA, examples.

“Overall, the presence of a marking increased the distance of cyclists to parked cars by 8 inches.”

“When passing vehicles were present, the markings caused an increase of 3 to 4 inches in the distance between cyclists and parked cars. In addition, the markings caused an increase of over 2 feet in the distance between cyclists and passing vehicles. The bike-and-chevron had a greater effect (by 3 inches) on the distance between cyclists and passing vehicles.”

“Before the arrow was placed, 39.3% of bicyclists rode in street, with traffic [versus on sidewalk.] After the arrow was placed, the proportion of bicyclists riding in street with traffic increased to 45.3%.”

Typical Applications

As shared lane markings are a relatively new bikeway marking in American cities, guidance on application will continue to evolve over time. Shared lane markings should not be considered a substitute for bike lanes, cycle tracks, or other separation treatments where these types of facilities are otherwise warranted or space permits. Shared lane markings can be used as a standard element in the development of bicycle boulevards to identify streets as bikeways and to provide wayfinding along the route.

Desirable shared lane marking applications:

To indicate a shared lane situation where the speed differential between bicyclist and motorist travel speeds is very low, such as:

On bicycle boulevards or similar low volume, traffic calmed, shared streets with a designed speed of < 25 mph.

The Toronto Cycling Study (2010) found that while 72.5% of all existing bicyclists are comfortable riding on major roads with bike lanes, only 54% reported feeling comfortable on major roads with sharrow markings.

Design Guidance

The Shared Lane Marking in use within the United States is the bike-and-chevron “sharrow,” illustrated in MUTCD figure 9C-9.

Shared Lane Markings shall not be used on shoulders, in designated bicycle lanes, or to designate bicycle detection at signalized intersections. (MUTCD 9C.07 03)

Recommended Features

Frequent, visible placement of markings is essential. The number of markings along a street should correspond to the difficulty bicyclists experience taking the proper travel path or position. SLMs used to bridge discontinuous bicycle facilities or along busier streets should be placed more frequently (50 to 100 feet) than along low traffic bicycle routes (up to 250 feet or more). SLMs used along low volume routes can be staggered by direction to provide markings closer together. Read More+

Lateral placement is critical to encourage riders to avoid the “door zone” and to encourage safe passing behavior. MUTCD guidance recommends minimum placement when a parking lane is present at 11 feet from the curb face. Read More+

“When sharrows were placed in the center of the lane, a significant change occurred in average bicyclist lateral position, away from the curb and towards the center of the lane. This result was significant both when bicyclists were being passed by motor vehicles and when no passing was occurring, but was more pronounced in the latter instance.”
The Center for Transportation Research, The University of Texas at Austin. (2010). Effects of Shared Lane Markings on Bicyclist and Motorist Behavior along Multi-Lane Facilities.

If used in a shared lane with on-street parallel parking, Shared Lane Markings should be placed so that the centers of the markings are at least 11 feet from the face of the curb or from the edge of the pavement where there is no curb.

On streets with posted 25 mph speeds or slower, preferred placement is in the center of the travel lane to minimize wear and encourage bicyclists to occupy the full travel lane.

On streets with posted 35 mph speeds or faster and motor vehicle volumes higher than 3,000 vpd shared lane markings are not a preferred treatment. On these streets other bikeway types are preferred.

If on-street vehicle parking is not present, SLMs should be placed far enough from the curb to direct bicyclists away from gutters, seams, and other obstacles. On streets with posted 25 mph speeds or slower, preferred placement is in the center of the travel lane to minimize wear and encourage bicyclists to occupy the full travel lane. MUTCD guidance recommends minimum placement with no parking at 4 feet from the curb face. Read More+

If used on a street without on-street parking that has an outside travel lane that is less than 14 feet wide, the centers of the Shared Lane Markings should be at least 4 feet from the face of the curb or from the edge of the pavement where there is no curb.

For wayfinding purposes the orientation of the chevron marking may be adjusted to direct bicyclists along discontinuous routes.

Color may be used to enhance the visibility of the shared lane marking and to further encourage desired lane positioning. Read More+

Salt Lake City, UT, and Long Beach, CA, have used a carpet of green coloring to create a lane-within-a-lane to indicate the priority area and preferred riding placement for bicyclists.

“The green lane facility has appeared to result in an approximate doubling of usage over the first 12 months of existence.”

“Bicyclists familiar with more traditional sharrows have noted that the additional emphasis resulting from the green pavement paint appears to be creating an heightened awareness by the motorists in the lane.”

In an evaluation of a lane-within-a-lane treatment in Sald Lake City, researches found that “Eleven months after implementation, the fraction of in‐street cyclists riding in the preferred zone, at least 4 ft from the curb, had risen from 17% to 92%.”